Structure and physical properties of nonstoichiometric rare-earth cadmium antimonides, RECd1−xSb2 (RE=La, Ce, Pr, Nd, Sm)

The ternary rare-earth cadmium antimonides RECd1−xSb2 (RE=La, Ce, Pr, Nd, Sm) were prepared by reaction of the elements at 1000 °C. The presence of Cd defects, previously found for LaCd0.700(5)Sb2 and CeCd0.660(4)Sb2, has been confirmed by single-crystal X-ray diffraction studies for the isotypic compounds PrCd0.665(3)Sb2(a=4.3592(3)Å, c=10.8619(7)Å), NdCd0.659(3)Sb2(a=4.3456(4)Å, c=10.8372(9)Å), and SmCd0.648(3)Sb2(a=4.3185(4)Å, c=10.7843(11)Å). These compounds adopt the HfCuSi2-type structure (Pearson symbol tP8, space group P4/nmm  , Z=2Z=2). The electrical and magnetic properties of samples with nominal composition RECd0.7Sb2 were investigated. All exhibit metallic behaviour, but CeCd0.7Sb2 undergoes an abrupt drop in its electrical resistivity below 3 K. LaCd0.7Sb2 exhibits temperature-independent Pauli paramagnetism and SmCd0.7Sb2 displays van Vleck paramagnetism. The remaining compounds obey the modified Curie–Weiss law at high temperatures. CeCd0.7Sb2 undergoes ferromagnetic ordering below 3 K, reaching a saturation magnetization of ∼1.0 μB, whereas PrCd0.7Sb2 and NdCd0.7Sb2 remain paramagnetic down to 2 K.

Graphical AbstractRECd1−xSb2 adopts the HfCuSi2-type structure, with layers of condensed CdSb4 tetrahedra and Sb square nets.Figure optionsDownload as PowerPoint slide